PCB Piezotronics CS640B94, Manual, Page: 10 / 27

PAGE 6
S
E
N
S
O
R
S
AND
INS
T
R
UM
E
NT
AT
IO
N F
O
R
MACHIN
E
CO
NDIT
IO
N
MON
ITO
RI
NG
If using a standard DC power supply, install either an ammeter and/or load resistor in line with the return
connection to the black wire.
The resistor will generate a DC voltage that is proportional to current by:
V = IR
If R = 500

and I = 6mA, then V = 3Vdc
Note:
- Resistor value must be less than: (Vsupply
– 12) x 50.
Taking Measurements
When measuring the current output from the unit, use the following formula to calculate the vibration level:
Vibration Output = (Measured Output
– 4mA) x (Full Scale Vibration Output /16mA)
Measured mA 640B90 640B91/B93 640B92/B94
4.00 0.0 ips, pk 0.0 ips, pk 0.0 ips, pk
8.00 0.125 ips, pk 0.25 ips, pk 0.5 ips, pk
12.0 0.25 ips, pk 0.5 ips, pk 1.0 ips, pk
15.75 0.37 ips, pk 0.73 ips, pk 1.47 ips, pk
20 0.5 ips, pk 1.0 ips, pk 2.0 ips, pk
Measured mA 641B90 641B91/B93 641B92/B94
4.00 0.0 ips, rms 0.0 ips, rms 0.0 ips, rms
8.00 0.125 ips, rms 0.25 ips, rms 0.5 ips, rms
12.0 0.25 ips, rms 0.5 ips, rms 1.0 ips, rms
15.75 0.37 ips, rms 0.73 ips, rms 1.47 ips, rms
20 0.5 ips, rms 1.0 ips, rms 2.0 ips, rms